Grayson Sinclair is part of the wealthy Sinclair family. He was married to Perdita Hyde-Sinclair and is the eldest son of Rosemary King and brother of Alasdair Sinclair. Grayson is the cousin of Lord Alex Oakwell.
He first appeared at a family dinner party with Perdy, Alasdair and Sadie King. He appeared again at Alasdair and Sadie's wedding and was present when Sadie and Rosemary agreed Sadie would annul her marriage to Alasdair in return for the Sinclair business that had the most sentimental value to Rosemary.
Grayson and Perdy got together, following the death of Perdy's brother, Harry. Harry died in action during the Bosnian war. He and Grayson were best friends. Rosemary told Tom King that Grayson and Perdy met at Harry's funeral and fell in love.
Perdy admitted to local vet, Hari Prasad, that Grayson was unfaithful. He had a gambling habit, which saw him sell some of Rosemary's paintings to Rodney Blackstock. He made friends with Diane Sugden and she accompanied him to casinos until Perdy asked Diane to take her husband Jack, not Grayson.
Grayson is an experienced solicitor advocate. He advised Bob Hope and the villagers about how they could sue King and Sons for the show home collapse but changed sides, defending the Kings when they were charged with corporate manslaughter.
Grayson found out Perdy has had five miscarriages. During a heart to heart, she confessed and seemed to resent his philandering.
Grayson is very close to his mother, Rosemary, due to the death of his father when Grayson and Alasdair were young. Rosemary, Grayson and Perdy lived at Oakwell Hall until Gray and Perdy bought Mill Cottage.
When Grayson was away, Perdy slept with Matthew King. Worried she was pregnant, she told Grayson and admitted Matthew could be the father. Luckily for their marriage, Perdy wasn't pregnant but the damage was done. Matthew and Grayson despised each other as Matthew felt Grayson was an idiot for not treating Perdy right while Grayson resented Matthew for trying to steal his wife. Matthew called Grayson, "Larry", a reference to comedian Larry Grayson, which Grayson hated. Matthew did this until he and Grayson had a fight over it. Matthew still did it but not to his face.
In December 2006, Paul Lambert rescued Grayson from a homophobic attack in Hotten. Paul asked Grayson why he had been attacked and Grayson confessed that he is bisexual. Paul, Grayson and Perdy bonded over the events of that night and became good friends. Grayson's other close friends were Diane Sugden and Katie Sugden. He and Diane bonded initially because they both enjoyed gambling and she took over as Grayson's motherfigure when Rosemary left the village. He and Katie became friends after Perdy bought a share of Katie's stable business. She was friends with Perdy first but got to know Grayson when she visited Mill Cottage and he helped her with her divorce from Andy Sugden.
Grayson and Perdy's marriage was always rocky but the final straw was when he had her sectioned. Unaware Rosemary was responsible for Perdy's illness, Grayson struggled to cope. Perdy refused to see him so Paul became go-between. In Perdy's absence, Rosemary ran Mill Cottage, looked after Grayson and helped Katie run the stables. Consequently, she and Rosemary became friends. Rosemary saw Katie had feelings for Grayson and encouraged her, hoping Grayson would move on and have a family. Katie, however, kept her distance as she refused to steal her best friend's husband.
Only Matthew knew Perdy was telling the truth about Rosemary and her illness but made her realise that to be released, she had to admit to her "illness". Perdy told Grayson that Rosemary was responsible but he didn't believe her until the family doctor backed her up. Grayson confronted his mother and threw her out so she moved in with Paddy Kirk briefly but disappeared after arguments with Grayson, Matthew and Zak Dingle. Fearing Rosemary, Perdy stayed with Matthew but when Rosemary admitted poisoning Perdy, Grayson begged Perdy to give their marriage another chance. She agreed, much to Matthew's disappointment, and began contacting surrogacy agencies to discover if they could have a family, despite Perdy's hysterectomy.
In October 2007, Rosemary's handbag and passport were seen under a bush when Edna was out walking Tootsie. A few days later, Paddy Kirk found them. He told the police and, in her diary, on the day of her disappearance, they found an entry "MK MF", which they guessed meant "Matthew King, Manor Farm". When the police searched the farm, they found coffee cups with Matthew and Rosemary's fingerprints and traces of her blood. They concluded Matthew asked Rosemary to meet him at Manor Farm, made her a coffee and killed her. Matthew was arrested and charged with Rosemary's murder and released on bail.
During October 2007, Perdy told Katie about her and Grayson's plans to hire an American surrogate, due to American law favouring genetic parents, unlike British law. Katie offered to be surrogate and they agreed. She and Matthew King tried talking Katie out of it and Matthew even offered to double the money that Grayson and Perdy would pay her but she refused. Touched by Katie's offer, Grayson asked her to move in with them. He wanted to look after her but Perdy was annoyed about her lack of time alone with Grayson. When Perdy found a negative pregnancy test, she and Matthew started making plans to get together but discovered that Katie had merely done a test too early. Perdy changed her mind about leaving as she wanted her baby, planning to leave once she had custody. Unfortunately, Grayson found out and framed Matthew for Rosemary's murder but Perdy found evidence of this and blackmailed Grayson into clearing Matthew and giving her sole custody of the baby. Matthew was released and Perdy moved into Home Farm with him.
Grayson was devastated to lose Perdy but Katie was furious. Worried about would happen to the baby, she threatened to have an abortion. Grayson persuaded Katie to keep the baby but told her about the blackmail so she became more friendly with Perdy. Perdy thought Katie was unhappy at Mill Cottage, given the amount of time she was spending at Home Farm. Thrilled and, feeling guilty, she admitted to the blackmail and Katie persuaded her to burn the cardigan before revealing that she and Grayson were an item and intended to keep the baby. Furious, Perdy physically attacked Katie, almost causing a miscarriage. Luckily, mother and baby were fine. Following this, Grayson warned Perdy she would have a fight for access, let alone custody, and told Matthew why Perdy and Katie had been fighting. Matthew was horrified to discover that Perdy knew Grayson was responsible for his imprisonment and knew about her blackmail. He threw her out, saying he never wanted to see her again. She moved in with Paul and Jonny as Paul was the only friend she had left in the village.
When Katie came home, Perdy dropped a bombshell - Grayson's bisexuality. Katie didn't believe her but Grayson admitted it. Diane warned Grayson he had to tell her the truth if he wanted a future with her. Katie was shocked but told Grayson that she would accept it as part of his past but insisted he stay faithful to her.
In late March 2008, Katie was due to go for a scan and suggested inviting Perdy but Grayson persuaded her not to and discovered that the baby was a boy. After the scan, Grayson and Katie went to the pub and told Diane. Jonny, Paul and Perdy saw them there and Perdy lost her temper when she heard their news. Trying to restrain Perdy, Paul and Jonny carried her outside but Grayson followed. They argued and Grayson told Perdy that he'd slept with Paul while she was in hospital so she attacked him and was arrested for assault, cautioned and released the next day. Perdy was angry with Paul and she left the area as Grayson had taken out a restraining order, insisting to Katie that it was in her and the baby's best interests.
A couple of months later, Perdy's solicitor and a friend of Grayson's, visited. Richard told Grayson that Perdy wanted custody and it would be best to settle out of court, giving Grayson Perdy's address in a rough part of Hotten. Feeling remorse for the way he had treated her, he got her a nicer flat and paid the rent. Worried about upsetting Katie, Grayson didn't tell her but she realised he was lying when, trying to help, she followed him with an important document. Realising Grayson was seeing Perdy, she suddenly realised why he was talking about Perdy and access agreements. Needing time, she went home but visited Perdy a few days later, wanting answers. Feeling some sympathy for Katie, she warned her that she couldn't trust Grayson and implied he only wanted her because she was pregnant. Katie now worried about the baby's future if she gave him to his natural parents.
When Katie confided in Chas Dingle about Grayson and Perdy's behaviour, Chas suggested Katie leave immediately but she decided to have the baby in London and put him up for adoption there. In the meantime, she tested Grayson by suggesting Perdy have custody. Unhappy, Grayson stormed out in a huff, making Katie think Perdy was right. She asked Chas to go with her and be her birth partner and Chas agreed. To make sure Grayson and Perdy didn't get suspicious, she agreed to Perdy having access and join them at the antenatal clinic but needed money for the London trip. Grayson was very well off so Katie claimed her mother had lost all her money. He wasn't happy about Katie's suggestion that she move in with them and suggested he pay her mother's debts. Katie agreed and asked him to give her the money, telling him she would send it to her mother. Claiming to be worried about finances, Katie suggested saving money by asking Perdy to move in. Grayson agreed so Perdy returned to Mill Cottage and started work at the stables.
Angry at Katie's deception, he confronted her and demanded she give him custody of his son but Jonny intervened so Katie got away. She soon realised she was in labour and asked Matthew to collect Perdy and take her to hospital but it was too late and she gave birth in the car. Perdy left Grayson a message, telling him what had happened. Katie was horrified when Perdy told her and gave the baby and the £20,000 to Perdy so they could leave. She convinced her (with Matthew's help), that she and the baby would be better off without Grayson. Matthew also distracted Grayson so they could get away. Grayson went after them but Perdy was already en route to the station. He got the hospital staff to phone the police and reported his son had been kidnapped. Katie told them Perdy was the baby's mother - she was just the surrogate - and gave them Perdy's mobile number. She confirmed that she and the baby were fine and asked them not to tell Grayson where she was.
He sank into self-pity and got drunk constantly. Chas found Grayson in a state and told Diane. She and Paul made him realise he had to pull himself together if he wanted to be a father and look for Perdy and the baby. Unfortunately Paul had promised Jonny that he wouldn't see Grayson so when Jonny saw them together, he was upset. Grayson saw him and, wanting to hurt Jonny, hugged Paul and thanked him for his help. Grayson went out, looking for fun, but was caught by the police. They charged him with indecent behaviour and released him. While drunk, Grayson locked himself and Katie into Victoria Cottage and demanded she tell him where Perdy was. Katie refused and escaped but he came after her, witnessed by Paul and Diane. He thought they would support him but Paul hit him for destroying his and Jonny's relationship. Nearly everyone saw this and when Donna Windsor-Dingle and Ross Kirk arrived, Grayson wanted Paul arrested. Unfortunately, nobody backed him up.
Ostracized, Grayson left the next day, warning Matthew and Chas he would be back. Chas told him to stay away from Katie unless he wanted to join Rosemary in the churchyard. Matthew laughed and told Grayson that he could have had it all but it was his own fault that Katie left him and gave his baby away.
Grayson returned in September, and took Matthew hostage. Matthew returned early from the village fair and, hearing a noise in the office, called out - thinking it was Katie. On checking, he found Grayson with a gun. He was also waiting for Katie. When she returned, Grayson held them both hostage, demanding they tell him where Perdy was but they refused. Grayson threatened to shoot Matthew but Katie still refused to tell him what he wanted to know. Jimmy and Carl King arrived later and he took them hostage too. They tried to calm him down and Carl tried talking to Grayson as one father to another but Grayson sneered at Carl for being a part-time father. Furious, Carl walked towards Grayson, daring him to shoot, which he did. Thankfully, Carl wasn't seriously injured. Jimmy and Matthew tackled Grayson, giving Katie the chance to grab the gun. At that point, she could have shot Grayson but Matthew persuaded her not to. Grayson allowed Katie to phone an ambulance but she called the police too and Grayson was arrested while trying to escape from Home Farm. Just before they left, in an unexpected kind gesture, Matthew gave Grayson the photo Perdy had sent him of her and the baby, for which Grayson thanked him.